Flash lamp and method of manufacture thereof



Aug; 21, 1945 M. PlPKlN I FLASH LAMP AND METHOD OF MANUFACTURE THEREOF Filed Dec. 31, 1941 lnvencor Marvin Pi pkm,

Hls Aft for'neg.

Patented Aug. 21', 19 45 msn LAMP AND METHOD OF MANU- rso'rune 'rnmmor Marvin Pinkin, Cleveland-Heights, Ohio, asslgnor to General Electric Company, a corporation of New York Application December 31, 1941, Serial No. 425,014

2 Claims.- (01.18-59) My invention relates in general to flash lamps or similar devices comprising a sealed enclosure, and to a method of manufacturing the same. More particularly, my invention relates to the construction of the enclosure for such flash lamps and similar devices.

In flash lamps in general use at present, the

enclosing bulb for the light-producing charge is usually made of glass or other vitreous material. Obviously, with such flash lamps there is always the danger of flying fragments of broken glass when the lamp, for some unexpected reason, explodes on charge flashing.

One object of my invention is to provide a flash lamp having a bulb made of a material such that the bulb will not break and shatter, so as to scatter flying fragments of the bulb, in the event an erplosition should occur upon flashing of the lamp.

Another object of my invention is to provide a method of manufacturing such a substantially nonbreakable and nonshatterable flash lamp.

Still another object of my invention is to provide a hash lamp having a bulb made of a relatively inexpensive material of such a nature that broken fragments thereof will not possess any sharp cutting surfaces such as are apt to produce bodily injury. i

A feature of my invention is the use of a bulb made of a suitable plastic material and sealed to the glass stem of the lamp mount structure.

Further objects and advantages of my invention will appear from the following description of species thereof and from the accompanying dra ."l m Fig. .1 ing my invention; Figs; 2, 3 and 4 are views illustrating the steps involved in manufacturing the hash lamp shown in Fig. 1; Fig. 5 is a fragmentary sectional view, on an enlarged scale, showing the completed seal between the bulb and stem of the lamp shown in Figs. 1-4; Big. 6 is an elevation of a modified form of flash lamp corn prising my invention; and Fig. l is a view illustrating one of the steps involved in manufacturing the modified form of flash lamp shown in Fig. ii, In the drawing, Figs. li illustrate the invention as applied to a flash lamp of the type disclosed and claimed in my copending application Serial No. 328,399, filed April 8, 1940, now Patent No. 2,291,983, in which. the source of actinic' ra... diation is constituted by one or more beads or compact masses of an agglutinated flashlight powder admixture disposed within the lamp bulb.

- Referring to Figs. 1-4, the flash lamp there shown comprises a bulb or envelope ill of a'sultable plastic material capable of transmitting radiations produced within the bulb by the lightgenerating means disposed therein and herein after described. The plastic material employed for the bulb may be any'of the well-known plastic materials, such as cellulose acetate, which possess the property of becoming soft either when immersed in a suitable solvent or when heated;' i. e., thermoplastic. The bulb In, if desired, may be coated on its outside and/or inside surface (preferably the inside) with a, suitable lacquer or similar material.

The bulb I0 is formed with a neck ii to which the glass stem l3 of a lamp mount structure I2 is sealed. The mount structure i2 comprises, in addition to the stem I3, a. pair ofleading-in wires it, ll sealed into the press portion it of the glass stem and provided with juxtapositioned inner lead portions Hi, It. Extending between the inner lead portions it, it and electrically connected thereto is an ignition filament ill of a suitable refractory metal, such as tungsten. Disposed on the tip of each innerlead it is a small compact mass or bead it of a suitable combustible material or fulminating substance which, upon ignition, produces a momentary hash of actinic light. At their outer ends, the leading-in wires H, M are connected to the terminals of a suitable base I9 cemented or otherwise suitably secured to the neck i i of the lamp bulb.

In the manufacture of the flash lamp shown around the periphery of a flange 20 formed on the stem l3 at the outer end thereof.

Referring to Fig. 3, showing one manner of sealing the bulb and the mount structuretogether, the flanged .end of the stem l3 and the neck end of the bulb are placed in a suitably shaped cup or container 2i in proper assembled interrelation, with the bulb neck surrounding the flange 20. The container H is filled with a suitable solvent 22 capable of softening the plastic material of which the bulb ill is made. Where cellulose acetate is used as the material for the bulb it, the solvent 22 may consist of, for inacetone. As the bulb neck gredunlly and acquires o. tacky condition, it tends rink down onto and adhere to the rim or oral edge of the flange 29 on the stem. 0 attached bulb and mount structure ere suitable lacquer or similar material around the seal, as shown in Fig. 5.

After the mount 62 has been sealed into the bulb, the base i9 is cemented or otherwise secured to the bulb neck end the lending-in wires M, i i suitably cormected to the terminals 01 the bose, by soldering, thus completing the flash lamp. nsteed of plechw both the bulb l8 and the mount structure E2 in assembled relation in the solvent 22, the bulb alone may be immersed in the solvent and after the neck becomes soft, the bulb removed from the solvent, the mount E2 inserted in piece within the bulb, and the bulb while still soft and plieble, then pressed into engagement with the rim or peripheral edge of the stem fionge 20, as before. With this method,

however, it is necessary that the bulb neck be made of such on internal diameter that, after the softening and shrinkage of the bulb neck, the internal diameter thereof will still be sufilcient to permit entryof the stem flonge 2h thereinto. Where the plastic material used for the bulb W possesses the property of becoming soft upon the application of heat thereto, then the softening of the bulb heel: it may be efiected instead by hosting the some in e suitable manner, as by conduction from a heating element in contact with the bulb neck. After the bulb neck has thus softened, the lump mount structure 82 is inserted its place within the bulb and the stem 53 e'ttwched and sealed to the softened neck by pressing letter down onto the peripheral edge of the flange 26, as before.

, gs. fi-l illustrate the invention as applied to l Lamp of the tygxe in which a quantity of readily ighitoble motel, in the form of 9. thin foil pressing the solte ooesore or in filamentary form, is throughout lamp bulb. 3 once of the loosely distributed rial 25, the shown in i "rise is substantially the some Fig. l. The combustible motel consists of aluminum or mag thereof, in illouientory form.

The manufacture of the lamp is subston' the lnebove in connection difference that bulb with the colirhustlble materiel 7, beiole the mount structure 52 thereinto. After the bulb 16 has been so oiled with the combustible material 26, the mount structure it? is then settled into the bulb by any of the methods disclosed herolnebove in connecelg; disposed 301 the presuctihle motetion with Figs. 1 to 4.

What I claim new and desire to secure by Letters FPoteht of the United States is:

1. In the manufacture of a. l: comprising a, bulb of organic plastic material a. mount structure comprising o. flanged stem tube luring an exhaust tube depending therefrom, the steps which comprise assembling the mount and bulb with the stem tube tclescoped in the bull: neck and with the lower end of the bulb roe-cl: and the adjoining stein located on ennulcr trough-shogoed container coziteln g a. solvent for the material of the bulb and with e exhaust tube extending through the central hing in it e ermulertr ebyhulh clsio softened by the solv... I rcunl .1 cm flange, removing the oh, and then cl no 3: portion into firm engagement with the stem 2. A flush lamp of the type to gzrioing o. bulb having a. compact body of agglutinated materiel supported therein coniprlslnz combustible and e. supgtorter of combustion intimately ossocieted with each other, and electrical means at least portion of which is is: contact with said body for developing an ignition temperature 

